The present disclosure relates to a power storage device, a power system and an electric vehicle using the power from the power storage device.
In recent years, use of a secondary battery such as a lithium ion battery has rapidly extended to a power storage device for electric power storage, storage battery for a vehicle and the like in which a new energy system such as solar batteries and wind power generation are combined. When using a plurality of electric storage elements for example, a unit battery (also, referred to as a single battery or a cell. Referred to as a battery cell in the description below as appropriate) for generating a large output, a configuration is employed in which a plurality of electric storage modules is connected in series. The electric storage modules configure a battery block by connecting a plurality of battery cells, for example, four, in parallel and/or in series. The electric storage module (also referred to as an assembled battery) is configured by enclosing a plurality of battery blocks in an outer case.
Further, a power storage device is known in which a plurality of electric storage modules is connected and a common control device (referred to as a main microcontroller unit as appropriate) is provided in a plurality of electric storage modules. The power storage device is configured such that each electric storage module has a module controller and communication is made between a module controller and the main microcontroller unit via a communication path.
Each electric storage module has the module controller consisting of a monitoring circuit and a microcomputer (referred to as a sub-microcontroller unit appropriately) to monitor the state of the battery cell and to detect abnormalities. The monitoring circuit monitors the voltage of each battery cell, compares a predetermined threshold value and a voltage of each battery cell using a comparator, and outputs a detection signal (for example, a 1-bit detection signal) indicating normality/abnormality thereof.
When charging the battery, the voltage of each battery cell is compared to a predetermined value and a detection signal, which illustrates whether or not the voltage is an overvoltage (referred to as OV appropriately), is generated. When discharging the battery, the voltage of each battery cell is compared to a predetermined value and the detection signal, which illustrates whether or not the voltage is an undervoltage (referred to as UV appropriately), is generated. When charging and discharging the battery, the current value flowing in the battery cell is compared to a predetermined value and the detection signal, which illustrates whether or not the current is an overcurrent (referred to as OC appropriately), is generated. Further, when charging and discharging the battery, the temperature of each battery cell is compared to a predetermined value respectively and the detection signal, which illustrates whether or not the temperature is in an overtemperature state (referred to as OT appropriately), is generated.
Further, the voltage and current of each battery cell are supplied to the sub-microcontroller unit of each module and a balance adjustment is made in which the voltages of the plurality of battery cells are equalized. The detection signal of the monitoring circuit described above is supplied to the sub-microcontroller unit via the communication path. Further, the detection signal is transmitted from the sub-microcontroller unit to the main microcontroller unit via the communication path. The main microcontroller unit receives the detection signal from each electric storage module and controls the charging and discharging operation.
For example, a DC power supply system for a vehicle consisting of a battery module having a group of a plurality of battery cells and a cell controller connected to the battery module is disclosed in PTL 1. The cell controller disclosed in PTL 1 has an integrated circuit having the same function as the monitoring circuit described above.